Over-end winding of yarn



United States Patent US. Cl. 57-156 6 Claims ABSTRACT OF THE DISCLOSURE Patterning in a yarn package, due to e.g. ring-tilt, is reduced by varying the spindle speed at a frequency dependant on the traverse time.

The invention concerns improvements in or relating to the over-end winding of yarn.

Over-end winding of yarn, as on the well-known ring spinning machine, is practised when it is desired to impart a twist to the yarn by the act of winding.

A common instance of such over-end winding is to be found in the drawtwisting of synthetic polymer filaments; and the present invention will be described in relation to such drawtwisting, although it is to be understood that the invention is not limited thereto.

A drawtwister is essentially a downtwister in which are incorporated roll mechanisms for drawing undrawn yarn. Usually, such mechanisms consist of nip rolls rotated at a given speed acting as feed rolls; and a draw roll and separator roll combination, the former roll of which is rotated at the required higher speed to effect the drawing action on the filaments in question. From the draw roll, the drawn filaments proceed in a generally downward direction to a thread guide positioned axially, or nearaxially, of the spindle of a ring and traveller ring spinning mechanism. This thread guide is sometimes known as the balloon guide, as the yarn is ballooned beneath it by virtue of the rotation of the traveller around the ring. The filaments are then wound up on a bobbin mounted on the rotating spindle, by passage around the traveller which is itself rotated around the ring and by reciprocation of the ring, in its rail, tray or other carrier, in the axial direction of the spindle according to the builder motion required for the particular yarn package to be wound on the bobbin.

It is a quite usual artifice to tilt the ring of the ring spinning mechanism in order that the filaments shall be laid on to the bobbin and yarn package in helical coils having a wavy path rather than a flat helical one. An angle of tilt of between 3 and 6 is usual; although an angle even as low as 1 may be selected and will donate an appreciable wave component to the laying-on 'path of the yarn. Rings are not generally set to a greater degree of accuracy than within 1 /2 Such ring tilt is at least a major factor predisposing the formation of regions of patterning at certain radii of the package build, owing to the coincidence of adjacent coil loci. The incidence of these various regions of patterning, which patterning is to be avoided both from the technical point of view of package stability and yarn take-off characteristics and from the point of view of appearance, can be calculated, e.g. by analogue computer, for any given process involving a drawtwisting wind-up; and hence it is possible to so programme the winding conditions that the regions of patterning which normally would occur shall be avoided.

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An alternative, or concomitant, approach to the reduction or avoidance of patterning, whether from natural or self-induced causes, consists in the rapid variation of one or more of the winding parameters, to bring about a scrambling of the winding conditions throughout the winding, in order continuously to modify the wave-form of the coils of yarn as laid on to the take-up package.

Thus, the spindle speed may be rapidly varied, by say, 10% about the mean value desired; and this rapid variation or scrambling, of the spindle speed will serve to break up patterning when it occurs at the calculable winding conditions during the formation of the package. Variation takes place in a cyclical manner about the mean spindle speed; and the number of cycles occurring in unit time is termed herein the frequency.

We have found, however, that with one fixed frequency of speed variation for the spindle speed, there is the disadvantage particularly with constant-rate traverse motions that conditions will recur during the winding when the ratio of spindle speed scrambling frequency to traverse frequency is a ratio of small numbers such as to lead, of itself, to patterning regions throughout large volumes of the package.

The present invention, therefore, is based on the proposition that it is necessary to control the spindle speed scrambling frequency during the winding so as to avoid the above-referred to whole number ratios, such control of scrambling frequency being achieved by monitoring it by, and directly in relation to, the traverse frequency, so as preferably to lead to a constant ratio of scrambling frequency to traverse frequency during the entire winding, such ratio not being a ratio of small whole numbers leading of itself to patterning.

The invention comprises a method of winding yarn by over-end winding on to a yarn package with the aid of a rotating spindle and a traversing means, wherein the speed of rotation of the spindle is varied cyclically about mean values thereof selected to be operative at given times during the winding of the package, or about a mean such value maintained constant throughout the winding, and wherein the frequency of such cyclical variation is monitored by, and is varied directly in relation to, the traversing frequency in such manner as to avoid any value of the ratio of said frequency to the traversing frequency ever being one consisting of small whole numbers (i.e. either of which is less than 5) such as would of itself lead to patterning occurring at given radii of the package during winding.

The means for monitoring the scrambling frequency by and in relation to the traverse frequency and for controlling it in consequence thereof according to a desired programme, usually referred to as programming means, may take any mechanical or electronic form convenient for the purpose and which is capable of sensing traverse frequency on a continuous basis and generating a scrambling frequency therefrom at a fixed ratio of frequencies, or at predetermined values of such ratio according to a desired programme.

Such a means may be a general purpose analogue computer, containing amplifiers, relays and comparator circuits and fed with signals identifying the instants in time of the bottom and top reversals of the drawtwister traverse motion. The output represents spindle speed containing the desired scrambling component, and is fed to the input of a speed-controlling servo-motor driving the spindles on the machine.

The specific method of continuously controlling spindle speed cycle time according to the invention may be combined with other expedients for the avoidance or reduction of patterning in over-end wound package.

Thus, the invention may be combined with other more radical programming of the spindle speed, e.g. whereby regions of patterning due to ring-tilt may be avoided. Equally, the invention may be combined with controlled or random variations in traveller speed and with yarn delivery speed.

Whilst the invention is applicable to the winding of yarn packages on all kinds of bobbin or tube, it will be understood that the particular programme to be selected will be affected by the shape of the tube, e.g. as to whether it is frusta-conical or cylindrical.

By way of example of the invention, the following details are given of a process for drawtwisting 100 denier 30 filament yarn of polyhexamethylene adipamide (nylon 6.6), at a draw ratio of 3.36 and a drawing speed of 2.646 feet/minute. The yarn was wound-up by a ringspinning mechanism with the ring tilted to 3 to the horizontal; and the yarn package was wound with a long-toshort traverse build, constant traverse speed of 23 inches/ minute. The spindle speed was programmed so as to reduce from an initial 9.750 r.p.m. to a final speed of 7,350 r.p.m.

In addition to the above programming, a rapid variation in spindle speed was programmed on to the spindle drive mechanism by an analogue computer, of an amplitude of 10% of the instant spindle speed. The programme was designed so that the ratio of scrambling" frequency to traverse frequency, say 3.52, remained constant at a given value throughout the winding, such value not representing a ratio of small whole numbers, i.e. whole numbers either of which is less than 5.

In another exemplary process, the yarn was produced and wound similarly to the above example, save that the spindle speed was scrambled i5% about the instant mean value, and the ratio of scrambling frequency to traverse frequency was 7.1.

Although an amplitude of is exemplified above for the variation in spindle speed, it will be understood by those skilled in the art that, as the severity of patterning in the various regions of it will not be uniform through the package, a lesser amplitude, say 3%-4%, may be adequate to disperse the patterning in certain of the regions; and thus, if the package is wound in such manner as to avoid the occurrence of patterning of the most severe nature, it may be possible, according to the invention, to employ such a lesser amplitude of spindle speed variation.

Likewise, it is within the scope of the invention to change the amplitude according to a programme, Whereby the higher amplitudes are selected at those times during the winding when calculation has determined that regions of severe patterning will take place, and lower amplitudes are selected for the other calculated regions.

The principle, so far as amplitude is concerned, is to use the lowest amplitude consonant with the achieveing of eifective dispersion of the patterns; so that amplitudes greater than, say, 15% will be unlikely to be needed or desirable.

We are aware of our co-pending application Serial No. 661,770, filed on even date herewith which discloses the use of more than one scrambling frequency and a method by which the spindle speed is varied at such plurality of scrambling frequencies according to a desired programme of frequency shifts.

We claim:

1. In the method of winding yarn by over-end winding on to a package with the aid of a rotating spindle and a traversing means, in which method the speed of rotation of the spindle is varied cyclically about the desired mean value during the winding of the package, the improvement comprising continuously monitoring the traversing frequency and varying the frequency of the cyclical variations in spindle speed in direct proportion to the traversing frequency whereby regions of patterning in the package are reduced.

2. A method according to claim 1 in which the frequency of spindle speed cycling is varied, as the ratio of said frequency to the traversing frequency approaches values giving rise to any substantial degree of patterning, in a manner to avoid any value of said ratio ever being one consisting of small whole numbers either of which is less than 5.

3. A method according to claim 2 in which said ratio 1 is maintained constant during winding.

4. A method according to claim 1 in which the amplitude of said cyclical variation in spindle speed is be tween 3% and 15% of the instant mean spindle speed.

5. A method according to claim 4 in which the said amplitude is itself changed according to a programme during the period of winding.

6. A method of claim 1 wherein said monitoring step is effected by electronically sensing the instants in time of the top and bottom reversals of the traversing means to obtain a signal and wherein the frequency of spindle speed cycling is varied in accordance with a function of said signal.

References Cited UNITED STATES PATENTS 2,658,689 11/1953 Waldrop 242-18.1 3,137,987 6/1964 Potts 5755.5 3,235,191 2/1966 Engelman et al. 242-l8.1 3,241,779 3/1966 Bray et al. 242--18.1 3,325,985 6/1967 Bucher 24226.3 XR

JORDAN FRANKLIN, Primary Examiner.

WERNER H. SCHROEDER, Assistant Examiner.

U.S. Cl. X.R. 

